Presentation architecture for network supporting implantable cardiac therapy device

ABSTRACT

A cardiac therapy network architecture collects data output by an implantable cardiac therapy device, processes that data, and distributes it to various knowledge workers. The cardiac therapy network implements a presentation architecture that formats and encodes the data using different formats and protocols to facilitate distribution to and presentation on various computing devices that might be utilized by the knowledge workers.

TECHNICAL FIELD

The present invention generally relates to implantable cardiac therapydevices and ways to present information obtained from the implantabletherapy devices.

BACKGROUND

Implantable cardiac therapy devices (ICTDs) are implanted within thebody of a patient to monitor, regulate, and/or correct heart function.ICTDs include implantable cardiac stimulation devices (e.g., implantablecardiac pacemakers, implantable defibrillators) that apply stimulationtherapy to the heart as well as implantable cardiac monitors thatmonitor heart activity.

ICTDs typically include a control unit positioned within a casing thatis implanted into the body and a set of leads that are positioned toimpart stimulation and/or monitor cardiac activity. With improvedprocessor and memory technologies, the control units have becomeincreasingly more sophisticated, allowing them to monitor many types ofconditions and apply tailored stimulation therapies in response to thoseconditions.

ICTDs are typically capable of being programmed remotely by an externalprogramming device, often called a “programmer”. Today, individual ICTDsare equipped with telemetry circuits that communicate with theprogrammer. One type of programmer utilizes an electromagnetic wand thatis placed near the implanted cardiac device to communicate with theimplanted device. When used in a sterile field, the wand may be enclosedin a sterile sheath. The wand contains a coil that forms a transformercoupling with the ICTD telemetry circuitry. The wand transmits lowfrequency signals by varying coil impedance.

Early telemetry systems were passive, meaning that the communication wasunidirectional from the programmer to the implanted device. Passivetelemetry allowed a treating physician to download instructions to theimplanted device following implantation. Due to power and sizeconstraints, early commercial versions of the implanted devices wereincapable of transmitting information back to the programmer.

As power capabilities improved, active telemetry became feasible,allowing synchronous bi-directional communication between the implanteddevice and the programmer. Active telemetry utilizes a half-duplexcommunication mode in which the programmer sends instructions in apredefined frame format and, following termination of this transmission,the implanted device returns data using the frame format. With activetelemetry, the treating physician is able to not only program theimplanted device, but also retrieve information from the implanteddevice to evaluate heart activity and device performance. The treatingphysician may periodically want to review device performance or heartactivity data for predefined periods of time to ensure that the deviceis providing therapy in desired manner. Consequently, current generationimplantable cardiac therapy devices incorporate memories, and theprocessors periodically sample and record various performance parametermeasurements in the memories.

Data pertaining to a patient's cardiac condition is gathered and storedby the programmer during programming sessions of the ICTDs. Analysis ofthe cardiac condition is performed locally by the programming software.Programmers offer comprehensive diagnostic capabilities, high-speedprocessing, and easy operation, thereby facilitating efficientprogramming and timely patient follow-up.

In addition to local analysis, TransTelephonic Monitoring (TTM) systemsare employed to gather current cardiac data from patients who are remotefrom the healthcare provider. TTM systems are placed in patients' homes.They typically include a base unit that gathers information from theICTD much like the programmer would. The base unit is connected to atelephone line so that data may be transmitted to the medical staffresponsible for that patient. An example of an ICTD TTM system is aservice from St. Jude Medical® and Raytel® Cardiac Services called“Housecall™.” This service provides current programmed parameters andepisode diagnostic information for a plurality of events includingstored electrograms (EGMs). Real-time EGMs with annotated statusinformation can also be transmitted.

Using a telephone and a transmitter, the TTM system provides both themedical staff and the patient the convenience of instant analysis oftherapy without having the patient leave the comfort of home. Typically,real-time measurements are transmitted in just minutes. Patients may beclosely monitored, and the medical staff has more control of theirpatient's treatment, thus administering better patient management.

One challenge that still persists, however, is how to efficiently andeffectively present patient information and cardiac data to medicalpersonnel and other knowledge workers who might have an interest in thedevice data. People utilize different types of computing devices toreceive and view data, such as computers, portable computers, personaldigital assistants, facsimile machines, and so on. These computingdevices have different user interface capabilities and features.Accordingly, there is a need for a system that delivers the data to awide variety of computing devices.

SUMMARY

A cardiac therapy network architecture collects data output by one ormore implantable cardiac therapy devices, processes that data, anddistributes it to various knowledge workers. The cardiac therapy networkimplements a presentation architecture that formats and encodes the datausing different formats and protocols to facilitate distribution to andpresentation on various computing devices with different user interfacecapabilities.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic illustration of a cardiac therapy networkarchitecture with an implantable cardiac therapy device (ICTD) connectedto a network of computing systems used by various knowledge workers.

FIG. 2 is a functional diagram illustrating information flow from theICTD to the computing systems associated with the knowledge workers.

FIG. 3 is a functional diagram illustrating how the various computingsystems share pieces of information to improve care given to thepatient.

FIG. 4 is a functional diagram illustrating information flow from thecomputing systems back to the ICTD.

FIG. 5 is a simplified illustration of an ICTD in electricalcommunication with a patient's heart for monitoring heart activityand/or delivering stimulation therapy.

FIG. 6 is a functional block diagram of an exemplary implantable cardiactherapy device.

FIG. 7 is a functional block diagram of an exemplary computing devicethat may be used in the computing systems of the cardiac therapy networkarchitecture.

FIG. 8 illustrates a presentation architecture implemented by thenetwork architecture to facilitate distribution and presentation ofinformation from the ICTD to the knowledge workers.

FIG. 9 is a functional block diagram of an exemplary presentation systemto format and encode content for delivery to the knowledge workers.

FIG. 10 is a flow diagram of a method for presenting content to theknowledge workers.

In the description that follows, like numerals or reference designatorsare used to reference like parts or elements.

DETAILED DESCRIPTION

The following description sets forth a cardiac therapy networkarchitecture in which data collected from an implantable cardiac therapydevice is processed and distributed to various knowledge workers. It isanticipated that the knowledge workers will utilize different computingdevices for receiving and viewing the data. These computing devices varywidely in terms of their user interface (UI) capabilities. Accordingly,the network architecture implements a presentation architecture thatformats and distributes content to various computing devices withdifferent user interface capabilities.

Cardiac Therapy Network

FIG. 1 shows an exemplary cardiac therapy network architecture 100 thatincludes an implantable cardiac therapy device (ICTD) 102 coupled to anetwork of computing systems associated with various knowledge workerswho have interest in cardiac therapy. The ICTD is illustrated as beingimplanted in a human patient 104. The ICTD 102 is in electricalcommunication with a patient's heart 106 by way of multiple leads 108suitable for monitoring cardiac activity and/or delivering multi-chamberstimulation and shock therapy.

The ICTD 102 may communicate with a standalone or offline programmer 110via short-range telemetry technology. The offline programmer 110 isequipped with a wand that, when positioned proximal to the ICTD 102,communicates with the ICTD 102 through a magnetic coupling.

The ICTD 102 can alternatively, or additionally, communicate with alocal transceiver 112. The local transceiver 112 may be a device thatresides on or near the patient, such as an electronic communicationsdevice that is worn by the patient or is situated on a structure withinthe room or residence of the patient. The local transceiver 112communicates with the ICTD 102 using short-range telemetry orlonger-range high-frequency-based telemetry, such as RF (radiofrequency) transmissions. Alternatively, the local transceiver 112 maybe incorporated into the ICTD 102, as represented by dashed line 111. Inthis case, the ICTD includes a separate and isolated package area thataccommodates high-frequency transmissions without disrupting operationof the monitoring and stimulation circuitry.

Depending upon the implementation and transmission range, the localtransceiver 112 can be in communication with various other devices ofthe network architecture 100. One possible implementation is for thelocal transceiver 112 to transmit information received from the ICTD 102to a networked programmer 114, which is connected to network 120. Thenetworked programmer 114 is similar in operation to standaloneprogrammer 110, but differs in that it is connected to the network 120.The networked programmer 114 may be local to, or remote from, the localtransceiver 112; or alternatively, the local transceiver 112 may beincorporated into the networked programmer 114, as represented by dashedline 116.

Another possible implementation is for the local transceiver to beconnected directly to the network 120 for communication with remotecomputing devices and/or programmers. Still another possibility is forthe local transceiver 112 to communicate with the network 120 viawireless communication, such as via a satellite system 122.

The network 120 may be implemented by one or more different types ofnetworks (e.g., Internet, local area network, wide area network,telephone, cable, satellite, etc.), including wire-based technologies(e.g., telephone line, cable, fiber optics, etc.) and/or wirelesstechnologies (e.g., RF, cellular, microwave, IR, wireless personal areanetwork, etc.). The network 120 can be configured to support any numberof different protocols, including HTTP (HyperText Transport Protocol),TCP/IP (Transmission Control Protocol/Internet Protocol), WAP (WirelessApplication Protocol), Bluetooth, and so on.

A number of knowledge workers are interested in data gathered from theimplantable cardiac therapy device 102. Representative knowledge workersinclude healthcare providers 130, the device manufacturer 132, clinicalgroups 134, and regulatory agencies 136. The knowledge workers areinterested in different portions of the data. For instance, thehealthcare providers 130 are interested in information pertaining to aparticular patient's condition. The manufacturer 132 cares about how thedevice is operating. The clinical groups 134 want certain data forinclusion in patient populations that can be studied and analyzed. Theregulatory agencies 136 are concerned whether the devices, and varioustreatments administered by them, are safe or pose a health risk.

The network architecture 100 facilitates distribution of the device datato the various knowledge workers. Information gathered from the deviceis integrated, processed, and distributed to the knowledge workers.Computer systems maintain and store the device data, and prepare thedata for efficient presentation to the knowledge workers. The computersystems are represented pictorially in FIG. 1 as databases. However,such system can be implemented using a wide variety of computingdevices, ranging from small handheld computers or portable digitalassistants (PDAs) carried by physicians to workstations or mainframecomputers with large storage capabilities. The healthcare providers 130are equipped with computer systems 140 that store and process patientrecords 142. The manufacturer 132 has a computer system 144 that tracksdevice data 146 returned from ICTDs 102. The clinical groups 134 havecomputer systems 148 that store and analyze data across patientpopulations, as represented by a histogram 150. The regulatory agencies136 maintain computer systems 152 that register and track healthcarerisk data 154 for ICTDs.

The network architecture 100 supports two-way communication. Not only isdata collected from the ICTD 102 and distributed to the various computersystems of the knowledge workers, but also information can be returnedfrom these computer systems to the networked programmer 114 and/or thelocal transceiver 112 for communication back to the ICTD 102.Information returned to the ICTD 102 may be used to adjust operation ofthe device, or modify therapies being applied by the device. Suchinformation may be imparted to the ICTD 102 automatically, without thepatient's knowledge.

Additionally, information may be sent to a patient notification device160 to notify the patient of some event or item. The patientnotification device 160 can be implemented in a number of waysincluding, for example, as a telephone, a cellular phone, a pager, a PDA(personal digital assistant), a dedicated patient communication device,a computer, an alarm, and so on. Notifications may be as simple as aninstruction to sound an alarm to inform the patient to call into thehealthcare providers, or as complex as HTML-based pages with graphicsand textual data to educate the patient. Notification messages sent tothe patient notification device 160 can contain essentially any type ofinformation related to cardiac medicinal purposes or device operation.Such information might include new studies released by clinical groupspertaining to device operation and patient activity (e.g., habits,diets, exercise, etc.), recall notices or operational data from themanufacturer, patient-specific instructions sent by the healthcareproviders, or warnings published by regulatory groups.

Notifications can be sent directly from the knowledge worker to thepatient. Additionally, the network architecture 100 may include anotification system 170 that operates computer systems 172 designed tocreate and deliver notification messages 174 on behalf of the knowledgeworkers. The notification system 170 delivers the messages in formatssupported by the various types of patient notification devices 160. Forinstance, if the patient carries a pager, a notification message mightconsist of a simple text statement in a pager protocol. For a moresophisticated wireless-enabled PDA or Internet-oriented cellular phone,messages might contain more than text data and be formatted using WAPformats.

FIG. 2 shows the flow of data from the implantable cardiac therapydevice 102 to the various computer systems used by the knowledgeworkers. Data from the ICTD is output as digital data, as represented bythe string of 0's and 1's. The data may consist of any number of items,including heart activity (e.g., IEGM), patient information, deviceoperation, analysis results from on-device diagnostics, and so on.

A data integrator 200 accumulates the data and stores it in a repository202. A processing system 204 processes portions of the data according tovarious applications 206 that are specifically tailored to place thedata into condition for various knowledge workers. For example,healthcare workers might be interested in certain portions of the data,such as the IEGM data and the patient information. Clinical scientistsmight be interested in the heart data, but do not wish to see anypatient information. Manufacturers may be interested in the raw datastream itself as a tool to discern how the device is operating.Depending on the needs of the end worker, the processing system 204takes the raw device data, evaluates its accuracy and completeness, andgenerates different packages of data for delivery to the variousknowledge workers. The processed data packages are also stored in therepository 202.

When the data is ready for delivery, a distribution/presentation system208 distributes the different packages to the appropriate computersystems 140, 144, 148, 152, and 172. The distribution/presentationsystem 208 is configured to serve the packages according to theprotocols and formats desired by the computer systems. In this manner,the network architecture 100 allows relevant portions of device data,collected from the ICTD, to be disseminated to the appropriate knowledgeworkers in a form they prefer.

Once the ICTD data is delivered, the computer systems 140, 144, 148,152, and 172 store the data and/or present the data to the knowledgeworker. The computer systems may perform further processing specific totheir use of the data. Through these processes, the knowledge workerscreate additional information that is useful to the patient, or otherknowledge workers with interests in ICTDs. For example, from the ICTDdata, the knowledge workers might devise improved therapies for a givenpatient, or create instructions to modify operation of a specific ICTD,or gain a better understanding of how implantable cardiac devicesoperate in general, or develop better technologies for futuregenerations of ICTDs. Much of this created knowledge can be shared amongthe various knowledge workers.

FIG. 3 shows how the various computing systems 140, 144, 148, 152, and172 can cooperate and share pieces of information to improve the caregiven to a patient. Where appropriate and legally acceptable, thecomputer systems may be configured to pass non-private information amongthe various knowledge workers to better improve their understanding ofthe implantable medical field. Clinical results 150 produced by theclinical computer systems 148 may be shared with healthcare providers toimprove patient care or with manufacturers to help in their design ofnext generation devices. The sharing of information may further lead tobetter and timelier healthcare for the patients.

If the collective knowledge base produces information that may provehelpful to the patient, that information can be passed to thenotification system 172 for delivery to one or more patients. Also, anyone of the knowledge workers may wish to employ the notification system172 to send messages to the patient(s).

FIG. 4 shows, in more detail, the flow of information back from thevarious computer systems used by the knowledge workers to theimplantable cardiac therapy device 102 or the patient notificationdevice 160. Information from any one of the computing systems—healthcarecomputer system(s) 140, manufacturer computer system(s) 144, clinicalcomputer system(s) 148, regulatory computer system(s) 152—or thenotification system 172 can be sent to a patient feedback system 400.The patient feedback system 400 facilitates delivery of the informationback to the patient. It may be an independent system, or incorporatedinto one or more of the computing. It may alternatively be integratedinto the notification system 172.

The patient feedback system 400 may be implemented In many ways. As oneexemplary implementation, the patient feedback system 400 is implementedas a server that serves content back to the networked programmer 114,which then uses the information to program the ICTD 102 through a builtin transceiver 116, local transceiver 112, or wand-based telemetry. Asanother possible implementation, the patient feedback system may be acellular or RF transmission system that sends information back to thepatient notification device 160.

The network architecture 100 facilitates continuous care around theclock, regardless of where the patient is located. For instance, supposethe patient is driving in the car when a cardiac episode occurs. TheICTD 102 detects the condition and transmits an alert message about thecondition to the local transceiver 112. The message is processed anddelivered to a physician's computer or PDA via the network 120. Thephysician can make a diagnosis and send some instructions back to thepatient's ICTD. The physician might also have a notification messagethat guides the patient to a nearest healthcare facility for furthertreatment sent via the notification system 170 to the patient'snotification device 160. Concurrently, the physician can share thepatient's records online with an attending physician at the healthcarefacility so that the attending physician can review the records prior tothe patient's arrival.

Exemplary ICTD

FIG. 5 shows an exemplary ICTD 102 in electrical communication with apatient's heart 106 for monitoring heart activity and/or deliveringstimulation therapy, such as pacing or defibrillation therapies. TheICTD 102 is in electrical communication with a patient's heart 106 byway of three leads 108(1)-(3). To sense atrial cardiac signals and toprovide right atrial chamber stimulation therapy, the ICTD 102 iscoupled to an implantable right atrial lead 108(1) having at least anatrial tip electrode 502, which typically is implanted in the patient'sright atrial appendage. To sense left atrial and ventricular cardiacsignals and to provide left chamber pacing therapy, the ICTD 102 iscoupled to a coronary sinus lead 108(2) designed for placement in thecoronary sinus region via the coronary sinus. The coronary sinus lead108(2) positions a distal electrode adjacent to the left ventricleand/or additional electrode(s) adjacent to the left atrium. An exemplarycoronary sinus lead 108(2) is designed to receive atrial and ventricularcardiac signals and to deliver left ventricular pacing therapy using atleast a left ventricular tip electrode 504, left atrial pacing therapyusing at least a left atrial ring electrode 506, and shocking therapyusing at least a left atrial coil electrode 508.

The ICTD 102 is also shown in electrical communication with thepatient's heart 106 by way of an implantable right ventricular lead108(3) having, in this implementation, a right ventricular tip electrode510, a right ventricular ring electrode 512, a right ventricular (RV)coil electrode 514, and an SVC coil electrode 516. Typically, the rightventricular lead 108(3) is transvenously inserted into the heart 102 toplace the right ventricular tip electrode 510 in the right ventricularapex so that the RV coil electrode 514 will be positioned in the rightventricle and the SVC coil electrode 516 will be positioned in thesuperior vena cava. Accordingly, the right ventricular lead 108(3) iscapable of receiving cardiac signals, and delivering stimulation in theform of pacing and shock therapy to the right ventricle.

FIG. 6 shows an exemplary, simplified block diagram depicting variouscomponents of the ICTD 102. The ICTD 102 can be configured to performone or more of a variety of functions including, for example, monitoringheart activity, monitoring patient activity, and treating fast and slowarrhythmias with stimulation therapy that includes cardioversion,defibrillation, and pacing stimulation. While a particular multi-chamberdevice is shown, it is to be appreciated and understood that this isdone for illustration purposes.

The circuitry is housed in housing 600, which is often referred to asthe “can”, “case”, “encasing”, or “case electrode”, and may beprogrammably selected to act as the return electrode for unipolar modes.Housing 600 may further be used as a return electrode alone or incombination with one or more of the coil electrodes for shockingpurposes. Housing 600 further includes a connector (not shown) having aplurality of terminals 602, 604, 606, 608, 612, 614, 616, and 618 (shownschematically and, for convenience, the names of the electrodes to whichthey are connected are shown next to the terminals).

To achieve right atrial sensing and pacing, the connector includes atleast a right atrial tip terminal (A_(R) TIP) 602 adapted for connectionto the atrial tip electrode 502. To achieve left chamber sensing,pacing, and shocking, the connector includes at least a left ventriculartip terminal (V_(L) TIP) 604, a left atrial ring terminal (A_(L) RING)606, and a left atrial shocking terminal (A_(L) COIL) 608, which areadapted for connection to the left ventricular ring electrode 504, theleft atrial ring electrode 506, and the left atrial coil electrode 508,respectively. To support right chamber sensing, pacing, and shocking,the connector includes a right ventricular tip terminal (V_(R) TIP) 612,a right ventricular ring terminal (V_(R) RING) 614, a right ventricularshocking terminal (RV COIL) 616, and an SVC shocking terminal (SVC COIL)618, which are adapted for connection to the right ventricular tipelectrode 510, right ventricular ring electrode 512, the RV coilelectrode 514, and the SVC coil electrode 516, respectively.

At the core of the ICTD 102 is a programmable microcontroller 620 thatcontrols various operations of the ICTD, including cardiac monitoringand stimulation therapy. Microcontroller 620 includes a microprocessor(or equivalent control circuitry), RAM and/or ROM memory, logic andtiming circuitry, state machine circuitry, and I/O circuitry.Microcontroller 620 includes the ability to process or monitor inputsignals (data) as controlled by a program code stored in a designatedblock of memory. Any suitable microcontroller 620 may be used. The useof microprocessor-based control circuits for performing timing and dataanalysis functions are well known in the art.

For discussion purposes, microcontroller 620 is illustrated as includingtiming control circuitry 632 to control the timing of the stimulationpulses (e.g., pacing rate, atrio-ventricular (AV) delay, atrialinterconduction (A—A) delay, or ventricular interconduction (V—V) delay,etc.) as well as to keep track of the timing of refractory periods,blanking intervals, noise detection windows, evoked response windows,alert intervals, marker channel timing, and so on. Microcontroller 220may further include various types of cardiac condition detectors 634(e.g., an arrhythmia detector, a morphology detector, etc.) and varioustypes of compensators 636 (e.g., orthostatic compensator, syncoperesponse module, etc.). These components can be utilized by the device102 for determining desirable times to administer various therapies. Thecomponents 632-636 may be implemented in hardware as part of themicrocontroller 620, or as software/firmware instructions programmedinto the device and executed on the microcontroller 620 during certainmodes of operation.

The ICTD 102 further includes an atrial pulse generator 622 and aventricular pulse generator 624 that generate pacing stimulation pulsesfor delivery by the right atrial lead 108(1), the coronary sinus lead108(2), and/or the right ventricular lead 108(3) via an electrodeconfiguration switch 626. It is understood that in order to providestimulation therapy in each of the four chambers of the heart, theatrial and ventricular pulse generators, 622 and 624, may includededicated, independent pulse generators, multiplexed pulse generators,or shared pulse generators. The pulse generators 622 and 624 arecontrolled by the microcontroller 620 via appropriate control signals628 and 630, respectively, to trigger or inhibit the stimulation pulses.

The electronic configuration switch 626 includes a plurality of switchesfor connecting the desired electrodes to the appropriate I/O circuits,thereby providing complete electrode programmability. Accordingly,switch 626, in response to a control signal 642 from the microcontroller620, determines the polarity of the stimulation pulses (e.g., unipolar,bipolar, combipolar, etc.) by selectively closing the appropriatecombination of switches (not shown).

Atrial sensing circuits 644 and ventricular sensing circuits 646 mayalso be selectively coupled to the right atrial lead 108(1), coronarysinus lead 108(2), and the right ventricular lead 108(3), through theswitch 626 to detect the presence of cardiac activity in each of thefour chambers of the heart. Accordingly, the atrial (ATR. SENSE) andventricular (VTR. SENSE) sensing circuits, 644 and 646, may includededicated sense amplifiers, multiplexed amplifiers, or sharedamplifiers. Each sensing circuit 644 and 646 may further employ one ormore low power, precision amplifiers with programmable gain and/orautomatic gain control, bandpass filtering, and a threshold detectioncircuit to selectively sense the cardiac signal of interest. Theautomatic gain control enables the ICTD 102 to deal effectively with thedifficult problem of sensing the low amplitude signal characteristics ofatrial or ventricular fibrillation. Switch 626 determines the “sensingpolarity” of the cardiac signal by selectively closing the appropriateswitches. In this way, the clinician may program the sensing polarityindependent of the stimulation polarity.

The outputs of the atrial and ventricular sensing circuits 644 and 646are connected to the microcontroller 620 which, in turn, is able totrigger or inhibit the atrial and ventricular pulse generators 622 and624, respectively, in a demand fashion in response to the absence orpresence of cardiac activity in the appropriate chambers of the heart.The sensing circuits 644 and 646 receive control signals over signallines 648 and 650 from the microcontroller 620 for purposes ofcontrolling the gain, threshold, polarization charge removal circuitry(not shown), and the timing of any blocking circuitry (not shown)coupled to the inputs of the sensing circuits 644 and 646.

Cardiac signals are also applied to inputs of an analog-to-digital (A/D)data acquisition system 652. The data acquisition system 652 isconfigured to acquire intracardiac electrogram signals, convert the rawanalog data into a digital signal, and store the digital signals forlater processing and/or telemetric transmission to an external device654. The data acquisition system 652 is coupled to the right atrial lead108(1), the coronary sinus lead 108(2), and the right ventricular lead108(3) through the switch 626 to sample cardiac signals across any pairof desired electrodes.

The data acquisition system 652 may be coupled to the microcontroller620, or other detection circuitry, to detect an evoked response from theheart 106 in response to an applied stimulus, thereby aiding in thedetection of “capture”. Capture occurs when an electrical stimulusapplied to the heart is of sufficient energy to depolarize the cardiactissue, thereby causing the heart muscle to contract. Themicrocontroller 620 detects a depolarization signal during a windowfollowing a stimulation pulse, the presence of which indicates thatcapture has occurred. The microcontroller 620 enables capture detectionby triggering the ventricular pulse generator 624 to generate astimulation pulse, starting a capture detection window using the timingcontrol circuitry 632 within the microcontroller 620, and enabling thedata acquisition system 652 via control signal 656 to sample the cardiacsignal that falls in the capture detection window and, based on theamplitude, determines if capture has occurred.

The microcontroller 620 is further coupled to a memory 660 by a suitabledata/address bus 662, wherein the programmable operating parameters usedby the microcontroller 620 are stored and modified, as required, inorder to customize the operation of the implantable device 102 to suitthe needs of a particular patient. Such operating parameters define, forexample, pacing pulse amplitude, pulse duration, electrode polarity,rate, sensitivity, automatic features, arrhythmia detection criteria,and the amplitude, waveshape and vector of each shocking pulse to bedelivered to the patient's heart 106 within each respective tier oftherapy. With memory 660, the ICTD 102 is able to sense and store arelatively large amount of data (e.g., from the data acquisition system652), which may transmitted to the external network of knowledge workersfor subsequent analysis.

Operating parameters of the ICTD 102 may be non-invasively programmedinto the memory 660 through a telemetry circuit 664 in telemetriccommunication with an external device, such as a programmer 110 or localtransceiver 112. The telemetry circuit 664 advantageously allowsintracardiac electrograms and status information relating to theoperation of the device 102 (as contained in the microcontroller 620 ormemory 660) to be sent to the external devices.

The ICTD 102 can further include one or more physiologic sensors 670,commonly referred to as “rate-responsive” sensors because they aretypically used to adjust pacing stimulation rate according to theexercise state of the patient. However, the physiological sensor 670 mayfurther be used to detect changes in cardiac output, changes in thephysiological condition of the heart, or diurnal changes in activity(e.g., detecting sleep and wake states, detecting position or posturalchanges, etc.). Accordingly, the microcontroller 620 responds byadjusting the various pacing parameters (such as rate, AV Delay, V—VDelay, etc.) at which the atrial and ventricular pulse generators, 622and 624, generate stimulation pulses. While shown as being includedwithin the device 102, it is to be understood that the physiologicsensor 670 may also be external to the device 102, yet still beimplanted within or carried by the patient. Examples of physiologicsensors that may be implemented in device 102 include known sensorsthat, for example, sense respiration rate and/or minute ventilation, pHof blood, ventricular gradient, and so forth.

The ICTD 102 additionally includes a battery 676 that provides operatingpower to all of circuits shown in FIG. 2. If the device 102 isconfigured to deliver pacing or shocking therapy, the battery 676 iscapable of operating at low current drains for long periods of time(e.g., preferably less than 10 μA), and is capable of providinghigh-current pulses (for capacitor charging) when the patient requires ashock pulse (e.g., preferably, in excess of 2 A, at voltages above 2 V,for periods of 10 seconds or more). The battery 676 also desirably has apredictable discharge characteristic so that elective replacement timecan be detected. As one example, the device 102 employs lithium/silvervanadium oxide batteries.

The ICTD 102 can further include magnet detection circuitry (not shown),coupled to the microcontroller 620, to detect when a magnet is placedover the device 102. A magnet may be used by a clinician to performvarious test functions of the device 102 and/or to signal themicrocontroller 620 that the external programmer is in place to receiveor transmit data to the microcontroller 620 through the telemetrycircuits 664.

The ICTD 102 further includes an impedance measuring circuit 678 that isenabled by the microcontroller 620 via a control signal 680. Uses for animpedance measuring circuit 678 include, but are not limited to, leadimpedance surveillance during the acute and chronic phases for properlead positioning or dislodgement; detecting operable electrodes andautomatically switching to an operable pair if dislodgement occurs;measuring respiration or minute ventilation; measuring thoracicimpedance for determining shock thresholds; detecting when the devicehas been implanted; measuring stroke volume; and detecting the openingof heart valves, etc. The impedance measuring circuit 678 isadvantageously coupled to the switch 626 so that any desired electrodemay be used.

In the case where the device 102 is intended to operate as animplantable cardioverter/defibrillator (ICD) device, it detects theoccurrence of an arrhythmia, and automatically applies an appropriateelectrical shock therapy to the heart aimed at terminating the detectedarrhythmia. To this end, the microcontroller 620 further controls ashocking circuit 682 by way of a control signal 684. The shockingcircuit 682 generates shocking pulses of low (up to 0.5 Joules),moderate (0.5-10 Joules), or high energy (11 to 40 Joules), ascontrolled by the microcontroller 620. Such shocking pulses are appliedto the patient's heart 106 through at least two shocking electrodes, andas shown in this implementation, selected from the left atrial coilelectrode 508, the RV coil electrode 514, and/or the SVC coil electrode516. As noted above, the housing 600 may act as an active electrode incombination with the RV coil electrode 514, or as part of a splitelectrical vector using the SVC coil electrode 516 or the left atrialcoil electrode 508 (i.e., using the RV electrode as a common electrode).

Cardioversion shocks are generally considered to be of low to moderateenergy level (so as to minimize pain felt by the patient), and/orsynchronized with an R-wave and/or pertaining to the treatment oftachycardia. Defibrillation shocks are generally of moderate to highenergy level (i.e., corresponding to thresholds in the range of 5-40Joules), delivered asynchronously (since R-waves may be toodisorganized), and pertaining exclusively to the treatment offibrillation. Accordingly, the microcontroller 620 is capable ofcontrolling the synchronous or asynchronous delivery of the shockingpulses.

The ICTD 102 may further be designed with the ability to supporthigh-frequency wireless communication, typically in the radro frequency(RF) range. As illustrated in FIG. 6, the can 600 may br configured witha secondary, isolated casing 690 that contains circuitry for handlinghigh-frequency signals. Within this separate case 690 are ahigh-frequency transceiver 92 and a diplexer 694. High-frequency signalsreceived by a dedicated antenna, or via leads 108, are passed to thetransceiver 692. Due to the separate casing region 690, the transceiverhandles the high-frequency signals in isolation apart from the cardiactherapy circuitry. In this manner, the high-frequency signals can besafely handled, thereby improving telemetry communication, withoutadversely disrupting operation of the other device circuitry.

Exemplary Computing Device

FIG. 7 shows an exemplary computing device 700 employed in the computingsystems of the cardiac therapy network architecture 100. It includes aprocessing unit 702 and memory 704. Memory 704 includes both volatilememory 706 (e.g., RAM) and non-volatile memory 708 (e.g., ROM, EEPROM,Flash, disk, optical discs, persistent storage, etc.). An operatingsystem and various application programs 710 are stored in non-volatilememory 708. When a program is running, various instructions are loadedinto volatile memory 706 and executed by processing unit 702. Examplesof possible applications that may be stored and executed on thecomputing device include the knowledge worker specific applications 206shown in FIG. 2.

The computing device 700 may further be equipped with a network I/Oconnection 720 to facilitate communication with a network. The networkI/O 720 may be a wire-based connection (e.g., network card, modem, etc.)or a wireless connection (e.g., RF transceiver, Bluetooth device, etc.).The computing device 700 may also include a user input device 722 (e.g.,keyboard, mouse, stylus, touch pad, touch screen, voice recognitionsystem, etc.) and an output device 724 (e.g., monitor, LCD, speaker,printer, etc.).

Various aspects of the methods and systems described throughout thisdisclosure may be implemented in computer software or firmware ascomputer-executable instructions. When executed, these instructionsdirect the computing device (alone, or in concert with other computingdevices of the system) to perform various functions and tasks thatenable the cardiac therapy network architecture 100.

Presentation Architecture

One feature of the network architecture is a presentation architecturethat enables presentation of data obtained from the implantable cardiactherapy device to various knowledge workers. The presentationarchitecture places the data in a suitable format and protocol toaccommodate different types of computing devices with different UIcapabilities. The presentation architecture separates the processing andpresentation functions so that decisions regarding how to present thecontent are made independently of the collection and processing of thedata.

FIG. 8 shows the presentation architecture 800 that is implemented bythe network architecture. The presentation architecture 800 has threelayers: an information source layer 802, a processing layer 804, and apresentation layer 806. The information source layer 802 provides thedata or information that is to be processed and presented to theknowledge worker. This layer includes data output by the ICTD, such asheart activity (e.g., IEGM), patient information, device operation data,analysis results from on-device diagnostics, and so on. It may furtherinclude other information made available for purposes of processing orbetter understanding the ICTD data.

The processing layer 804 performs the data handling and analyticalprocesses. This layer contains the applications and methods that conformthe data into content that will ultimately be presented to the knowledgeworkers. The processing layer 804 may include, for example, theprocessing system 204 and applications 206 that create the contentdesired by the knowledge workers.

The presentation layer 806 is responsible for getting the content to theknowledge worker in a form they prefer. This layer 806 contains theapplications and processes that determine which content to present towhom, the format of the content, and the protocol by which to send thecontent.

FIG. 9 shows one exemplary implementation of the presentation layer 806configured as the distribution/presentation system 208. The presentationlayer 806 enables effective delivery and presentation of content to manydifferent types of computing devices, as represented by exemplarydevices 900(1)-(8). It is anticipated that knowledge workers willutilize many diverse types of computing devices, including pagers900(1), personal digital assistants (PDAs) 900(2), Web-enabled or“smart” phones 900(3), portable computers 900(4), facsimile machines900(5), cellular phones 900(6), databases 900(7), and desktop computers900(8). These devices may be implemented using open standard softwareand protocols, or proprietary software and protocols.

The presentation layer 806 includes a content component store 902 tostore snippets of content ready to be presented to the knowledge worker.The content may include raw data, processed data, additional informationadded during processing, and so on. Although the content store 902 isillustrated in FIG. 9 as residing at the distribution/presentationsystem 208, it may also reside in the repository 202.

The presentation layer 806 may further include a content selector 904 tochoose the content components from store 902 for presentation to thevarious knowledge workers. For instance, the content selector 904 mayselect patient-related data (e.g., IEGM, therapy parameters, patientinformation, etc.) for presentation to healthcare workers. It mightfurther choose device-related information (e.g., raw IEGM data) forpresentation to the manufacturer.

The content selector 904 maintains a set of knowledge worker records 906in a database or other storage unit. The knowledge worker records 906specify the worker's contact information, information preferences, andcomputing resources. The records 906 track, for example, the worker'semail address, phone numbers, and pager numbers. The records 906 mightfurther specify the type of information desired by the knowledge workerand the type(s) of computing devices 900 that the knowledge worker uses.As one example, a record 906 for a cardiac physician may specify thecontact information, the doctor's preference to see IEGM data output bythe ICTD, and that the primary computing device is a Palm Pilot® PDA900(2) with wireless communication capabilities but limited UI features.

A user interface (UI) specification store 910 maintains the rules thatdictate how the content is to be presented on different computingdevices and software platforms. The computing devices 900(1)-(7) have awide variety of UI features and capabilities, ranging fromhigh-resolution color monitors, to single-line LCD displays or audioalarms, to database structures and facsimile machines.

The UI specification store 910 maintains one or more UI definitions 912that specify device requirements for visual/audio output. The UIdefinitions 912 include such parameters of whether devices have adisplay and if so, the display type (e.g., LCD, CRT, LED, etc.), displaysize, whether the display is capable of showing graphics and/or color,whether audio is possible, and so on. These UI definitions 912 help thecontent selector 904 identify which snippets of information in thecontent store 902 should be selected for a given device specified in theknowledge worker record 906.

The UI specification store 910 also includes one or more style sheets914 that specify how the content is to be arranged for a given computingdevice. The style sheets 914 specify the format of the information, suchas HTML, , SNMP (Simple Network Management Protocol), etc. The sheetsalso dictate the type of content that can be included, such as graphicalcomponents, text, audio, video, and so on.

The presentation layer 806 might also include a content formatter 920 toplace the content into the appropriate format specified by the UIspecification store 910 for a target computing device. For instance, ifa particular knowledge worker utilizes a laptop computer that is capableof receiving HTML documents, the content formatter 920 formats thecontent in HTML for effective presentation. If another knowledge workerhas a cellular phone, the content formatter 920 may format the contenttext that can be readily depicted on a limited display.

A delivery protocol encoder 922 encodes the formatted content accordingto the protocols supported by the computing devices and networks used bythe knowledge worker. There are many possible protocols, including HTTP,TCP/IP, WAP, Bluetooth, etc. Depending upon the preferences specified inthe knowledge worker records 906, the delivery protocol encoder 922encodes the content to the appropriate delivery protocol for subsequentdistribution to the devices operated by the knowledge workers.

Separating the presentation and processing layers and implementing UIdefinitions and style sheets enables the architecture to distributecontent produced by multiple applications to a wide assortment ofcomputing devices without requiring unique U's for each computingdevice. Suppose there are three applications that produce content to bedistributed to four different computing devices of the knowledgeworkers. If the presentation layer were integrated with the processinglayer, the application developer would need to write a specific UI foreach device, resulting in twelve different versions of UI code (i.e.,the number of applications times the number of devices).

By separating the presentation layer, however, independent UIdefinitions 912(1)-(3) can be developed to specify UI requirementsimposed by individual applications. Style sheets 910(1)-(4) can becreated to describe what features individual devices are able tosupport. Combining the UI definition with a style sheet dictates whatcontent is presented and how it is presented for a given computingdevice. In this example, the architecture allows, at most, the creationof seven definitions/sheets to facilitate presentation of content fromthree applications on four devices (i.e., the number of applicationsplus the number of devices), down from twelve separate versions.

This architecture is easily adopted to support new computing devices. Adeveloper defines a new UI definition and/or a style sheet to enablepresentation of content on the new device. This saves time and money inthat developers are not forced to modify applications as UI capabilitiesof the end-user computing devices change.

Presentation Operation

FIG. 10 shows a process 1000 for presenting content to the knowledgeworkers. Aspects of this process may be implemented in hardware,firmware, or software, or a combination thereof.

At block 1002, the distribution/presentation system 208 determines whatcomputing resources are available for the knowledge worker who isintended to receive the information. The system consults the knowledgeworker records 906 to identify the types of computing devices specifiedby the knowledge worker. At block 1004, the system ascertains thefeatures and capabilities of the computing resources of the intendedknowledge worker. Such features may include display type, display size,graphical capabilities, color capabilities, etc.

At block 1006, the content selector 904 selects the content to bedelivered to the knowledge worker based, in part, on the capabilities ofthe computing resources. For instance, if the knowledge worker iscarrying a PDA or phone of limited screen size, the content selector 904extracts summary statements or phrases from the content component store902 that can be presented on the device. For instance, the contentselector might choose a statement “IEGM for Patient X is ready forviewing”. Such a message would inform the knowledge worker thatpertinent patient data is ready for downloading next time the knowledgeworker is at a device capable of viewing and analyzing IEGM charts. Fordevices of higher capabilities (e.g., portable or desktop computer), thecontent selector may choose full data graphs and/or commentary topresent to the knowledge worker.

At block 1008, the content formatter 920 formats the selected contentinto suitable formats for presentation on the knowledge worker'scomputing device. Possible formats include HTML, XML, and SNMP. At block1010, the delivery protocol encoder 922 encodes the content according toa protocol supported by the target network and computing device.Examples of possible protocols include HTTP, TCP/IP, WAP, Bluetooth,etc. At block 1012, the system 208 delivers the content to the knowledgeworker's computing device, where it is presented for review and analysisby the knowledge worker.

Conclusion

Although the invention has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described. Rather,the specific features and acts are disclosed as exemplary forms ofimplementing the claimed invention.

1. A system comprising: an implantable cardiac therapy device; acomputing network configured to communicate with and receive data outputby the implantable cardiac therapy device and to distribute the data tocomputing devices associated with knowledge workers who are interestedin the data; and a presentation architecture implemented by thecomputing network to distribute the data to the computing devicesaccording to different formats and protocols supported by the computingdevices, the presentation architecture comprising: a processing layer toprocess the data received from the implantable cardiac therapy device;and a presentation layer, separate from the processing layer, to formatand encode the data according to the formats and protocols supported bythe computing devices.
 2. A system as recited in claim 1, wherein thepresentation architecture comprises: one or more records that specifythe computing devices used by the knowledge workers; and a specificationstore to maintain user interface definitions and style sheets specifyinghow the data should be presented on a particular computing device.
 3. Asysterm as recited in claim 1, wherein the presentation architecturecomprises: a content formatter to format the data in different formatsfor presentation on the computing devices; and a protocol encoder toencode the date according to different protocols supported by thecomputing devices.
 4. A system as recited in claim 1, wherein theimplantable cardiac therapy device comprises a cardiac stimulationdevice.
 5. A system as recited in claim 1, wherein the computing networkis configured to distribute the data to computing devices selected froma group of computing devices comprising a computer, a portable computer,a personal digital assistant, a wireless phone, facsimile, and adatabase.
 6. A presentation architecture for presenting data output byan implantable cardiac therapy device to various computing devicesoperated by knowledge workers who are interested in the data, thepresentation architecture comprising: an information source layar tocollect the data from the implantable cardiac therapy device; aprocessing layer to process the date collected by the information sourcelayer; and a presentation layer, separate from the processing layer, toformat and encode the data according to the different formats andprotocols supported by the computing devices.
 7. A presentationarchitecture as recited in claim 6, wherein the presentation layercomprises: one or more records that specify the computing devicesoperated by the knowledge workers; and a specification store to maintainuser interface definitions and style sheets specifying how the datashould be presented on a particular computing device.
 8. A system asrecited in claim 6, wherein the presentation layer comprises: a contentformatter to format the data for presentation on the computing devices;and a protocol encoder to encode the data according to differentprotocols supported by the computing devices.
 9. In a network system forgathering data from an implantable cardiac therapy device and processingthe data for distribution to various knowledge workers, a methodcomprising: ascertaining capabilities of computing resources availableto the knowledge workers, wherein different knowledge workers utilizedifferent types of computing device with different capabilities; anddistributing the data to the computing devices in accordance with apresentation architecture, the presentation architecture comprising: aprocessing layer to process the data received from the implantablecardiac therapy device; and a presentation layer, separate from theprocessing layer, to format and encode the data according to the formatsand protocols supported by the computing devices.
 10. A method asrecited in claim 9, further comprising choosing different portions ofdata to format and encode based on the capabilities of the computingdevices.
 11. A method as recited in claim 9, further comprisingmaintaining user interface and layout criteria for the computingresources.
 12. A method as recited in claim 9, wherein distributing thedata in accordance with the presentation architecture comprises:specifying the computing devices used by the knowledge workers with oneor more records; and maintaining user interface definitions and stylesheets in a specification store to specify how the data should bepresented on a particular computing device.
 13. A method as recited inclaim 9, wherein distributing the data in accordance with thepresentation architecture comprises: formatting the data in differentformats for presentation on the computing devices; and encoding the dataaccording to different protocols supported by the computing devices. 14.A method as recited in claim 9, wherein the data is distributed to thecomputing devices selected from a group comprising a computer, aportable computer, a personal digital assistant, a wireless phone, afacsimile, and a database.